/yoo ran"euh nuyt', -ray"neuh-/ , n.
a mineral, probably originally uranium dioxide, UO 2 , but altered by radioactive decay, and usually containing uranium trioxide, lead, radium, and helium, occurring in several varieties, including pitchblende: the most important ore of uranium.
[ 1875-80; URAN(IUM) + -IN 2 + -ITE 1 ]